WO1993021360A1 - Procede de refusion de surfaces de pieces par rayonnement laser - Google Patents

Procede de refusion de surfaces de pieces par rayonnement laser Download PDF

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Publication number
WO1993021360A1
WO1993021360A1 PCT/DE1993/000328 DE9300328W WO9321360A1 WO 1993021360 A1 WO1993021360 A1 WO 1993021360A1 DE 9300328 W DE9300328 W DE 9300328W WO 9321360 A1 WO9321360 A1 WO 9321360A1
Authority
WO
WIPO (PCT)
Prior art keywords
laser beam
workpiece
angle
remelting
incidence
Prior art date
Application number
PCT/DE1993/000328
Other languages
German (de)
English (en)
Inventor
Axel Zwick
Konrad Wissenbach
Original Assignee
Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. filed Critical Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Publication of WO1993021360A1 publication Critical patent/WO1993021360A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C26/00—Coating not provided for in groups C23C2/00 - C23C24/00
    • C23C26/02—Coating not provided for in groups C23C2/00 - C23C24/00 applying molten material to the substrate

Definitions

  • the invention relates to a method for remelting surfaces of workpieces with laser radiation, a laser beam striking the workpiece surface with an angle of incidence deviating from 0 °.
  • Such remelting of surfaces is used in the targeted surface modification of workpieces, for example to increase the wear or corrosion resistance.
  • the method is particularly suitable for remelting pre-coated surfaces, e.g. with foils, pastes, powders, spray layers etc., in particular in the presence of non-metallic binders which tend to degassing or evaporation or of alloying elements which tend to undergo violent chemical reactions.
  • the laser beam strikes the surface of the precoating perpendicularly and is partially absorbed there.
  • the heat is transported in depth by heat conduction and - if a weld pool is formed - by convection in the weld pool.
  • the fundamental disadvantage that the laser beam always strikes the precoating during the machining process and has to penetrate it until it can interact with the workpiece underneath (piercing process). Large parts of the precoating are lost, for example due to removal or evaporation, and are therefore not available for forming the desired alloy with the base material.
  • the invention has for its object to provide a method for remelting surfaces of workpieces with laser radiation according to the preamble of claim 1, in which the disadvantages mentioned are avoided. Furthermore, the invention is intended to enable remelting of pre-coated surfaces, in particular in the case of precoatings which tend to degass and / or to violent chemical reactions and / or are difficult to melt due to their hard material content. Another problem on which the invention is based is to increase the hard material content in the layer in the case of components subject to wear (e.g. tools) and thus to achieve an improvement in wear resistance.
  • a solution according to the invention is specified in the characterizing part of claim 1.
  • Advantageous refinements and developments, in particular for the preferred field of application of the invention, the remelting of pre-coated materials, are specified in subclaims 2 to 20.
  • the remelting rate, ie the remelted per unit time, is reduced Area, significantly increased and thus the process efficiency drastically increased.
  • the method according to the invention can be applied to all surfaces, in particular to all precoated surfaces.
  • the preferred field of application of the invention is remelting of pre-coated surfaces, this case will be dealt with in more detail below.
  • the precoat can be made using various techniques. The method is particularly effective for the treatment of complexly shaped and difficult to access areas of a component. In these cases, for example, films, tapes or suspended layers are suitable as a pre-coating.
  • the typical layer thicknesses are in the range of 0.1 to 10 mm.
  • the composition of the layer depends on the desired usage properties and the manufacturing process. Because of the production process and the type of application, such precoats often contain residues of binders and adhesives, and the moisture content is relatively high. Such contaminants evaporate or gasify during remelting and hinder the formation of a melt pool and / or lead to increased pore formation.
  • additives prevent the formation of a molten bath or melting additives evaporates in the layer or in the
  • the aim of the invention is to produce a maximum proportion of hard material (e.g. carbide) and / or a certain alloy concentration in the layer.
  • the process control must be designed in such a way that no hard materials or alloy elements are lost due to the interaction of the laser radiation with the layer (e.g. through burning, evaporation, blasting away).
  • the layer created after the laser beam treatment must be free of pores and cracks and have good adhesion to the substrate.
  • Fig. 1 processing directions when remelting a precoated workpiece
  • ig 7b reflectance / absorption as a function of the angle of incidence for different polarization states
  • FIG. 1 shows schematically different types of remelting of precoated materials.
  • the sectional illustration shows a surface area of a workpiece 1 which is made up of a base material 2 and a precoating 3 located thereover.
  • the workpiece 1 should be stationary be and the laser beam 4 striking the precoating 3 is guided over the workpiece surface at a feed speed v in the direction of the arrow, that is to say from left to right.
  • v in the direction of the arrow
  • the middle arrangement corresponds to the prior art mentioned at the outset with a laser beam 4 perpendicularly incident on the precoating 3.
  • the right arrangement shows a laser beam 4 which is incident in the opposite direction to the processing direction (a ⁇ 0), so that the remelting process takes place in a slow processing direction. Because of the angle of incidence, significantly more and more laser energy hits the precoating 3 directly. This is associated with a permanent piercing process, as is also the case with processing according to the prior art mentioned at the outset. With this method of processing, the same disadvantages can therefore be expected as are present in the prior art, ie the precoating 3 is removed, evaporated, burned or destroyed in some other way.
  • the arrangement on the left shows a laser beam 4 (a 0 0) incident in the machining direction, so that the remelting process takes place according to the invention in the piercing direction.
  • Foil filled with hard material can consist, for example, of a relatively soft but highly temperature-resistant Udimet 700 matrix material and TiC as hard material.
  • the basic sequence of the remelting process is shown in FIGS. 1 to 3.
  • a linear intensity distribution in the laser beam 4 is assumed, such as that produced by a line focusing mirror.
  • the laser beam 4 strikes the workpiece surface at an angle of incidence ⁇ of 10 ° a a 85 85 °.
  • the remelting process is started on the precoated workpiece 1 or, as shown in FIG. 2b, in a non-precoated zone of the workpiece 1 at an edge area of the precoating 3.
  • the laser radiation hits the precoating 3 directly (FIG. 2a) and is partially absorbed on the surface of the precoating.
  • the mechanisms then taking place which are also present in the method known from the prior art mentioned at the outset, are described in more detail below and are to be referred to as grooving.
  • the laser radiation strikes the surface of the base material 2 and a molten bath 6 is formed (FIG. 2c).
  • the laser beam 4 always hits the weld pool 6 on the workpiece surface first.
  • the degree of preheating is to be set via the angle of incidence and / or the angle of the direction of polarization, if polarized laser radiation is used, to the workpiece surface so that combustion, evaporation and gasification processes, e.g. matrix material or alloying elements can be avoided.
  • the preheating temperature must be set at least high enough that residues of additives undesirable in the alloyed layer 9, e.g. Binder and adhesive 10 are degassed.
  • the preheating temperature should be set such that the first individual melting drops 7 (for example the matrix material Udimet 700) form and wet the non-melted hard materials (for example TiC). These melt drops 7 are stored in the melt 6 and solidify, including the hard materials, to form a new layer composition, the alloyed layer 8. However, portions of the precoating 3 which cannot be melted also become through the melt pool 6 formed below the pre-coating 3 and by melt pool convection in the melt pool 6.
  • the layer thickness or the hard material portion and / or alloy portion can be set by the distance energy introduced (absorbed laser power / feed rate) and the thickness or composition of the precoating.
  • the proportion of the base material 2 in the melt pool volume should be chosen to be sufficiently high so that, for example, hard materials are distributed as homogeneously as possible by the melt pool convection and remaining residues of binders and adhesives can be degassed from the melt pool 6 and do not form any pores.
  • the reflected laser radiation 9 is used on the one hand, as already described above.
  • the remelting process according to the invention can be used for an alloying, dispersing or coating process.
  • the laser beam has an output of 4 kW on the workpiece and the feed speed v is 1,400 mm / min. 4a, a rectangular laser beam spot 12 is guided over the workpiece 1 in the direction of the arrow and leaves the unmelted surface in the form of a coating track 13.
  • An improvement in the processing result in particular in the case of reactive precoatings, can be achieved by tilting a rectangular-shaped laser beam 4 by an angle ⁇ .
  • the projection of the laser beam 4 onto the surface of the workpiece 1 with the machining direction or the coating track 13 already created encloses the angle ⁇ . Since this increases the reaction zone and the energy per remelted area with the same beam dimensions and laser powers there is a more favorable bath convection.
  • a further embodiment of the method according to the invention is shown in side view in FIG. 6 in a right-angled coordinate system (x, y, z), the y-axis emerging perpendicularly from the plane of the drawing.
  • the workpiece 1 is tilted by an angle gamma with respect to the horizontal, i. H. the lower workpiece plane, which lies in the plane formed by the axes a and y, has been rotated by the angle gamma in the direction of the z axis.
  • the laser beam 4 encloses the angle ⁇ with the tilted workpiece 1.
  • the feed direction is selected in the case shown here so that it is in the direction of the projection of gravity onto the workpiece surface, i.e. in the direction of the downhill force and thus parallel to the axis a.
  • the workpiece 1 is additionally rotated by an angle ⁇ about the axis a in the x, z plane, so that the weld pool is to a lesser extent than before against the Layer 3 is pressed.
  • the angle ⁇ must be set as a function of the angle ⁇ in such a way that the molten bath 6 does not lose contact with the precoating 3 and cannot flow away from the workpiece 1 transversely to the precoating.
  • the feed direction can also deviate from the aforementioned direction parallel to a and have a non-zero amount in the + y or -y direction.
  • the angle ⁇ is equal to zero and the feed direction is almost parallel to the y-axis, so that the coating track runs horizontally over the workpiece.
  • FIG. 7a schematically shows a laser beam 4 which strikes the workpiece 1 at an angle of incidence and in which the electric field vector E has a portion parallel to the plane of incidence, the plane of incidence being defined as the plane which is defined by the incident beam and the normal N. is stretched on the surface.
  • the portion of the incident laser beam 4 absorbed by the surface depends on its state of polarization and on the angle of incidence. This known relationship is shown graphically in FIG. 7b.
  • the curve for parallel polarization passes through an absorption maximum as a function of the angle of incidence, so that the degree of absorption can be set via the angle of incidence and the state of polarization.
  • angle of incidence ⁇ ⁇ ; 0 ° increases the impact surface and thus the power density decreases. This can be compensated for either by higher laser powers or more effectively by increasing the degree of absorption by using linearly polarized laser radiation.
  • linearly polarized laser radiation By using linearly polarized laser radiation, a significant increase in efficiency can even be achieved in the method according to the invention with a piercing machining direction if angles of incidence ⁇ ⁇ 30 ° are used.
  • Both cylindrical, curved and planar surfaces can be processed. In the case of cylindrical and curved components, the angle of incidence can be adjusted by offset from the respective axis of rotation. With planar surfaces, the angle must be specified by the optics or by the workpiece position.
  • FIG. 8 shows the influence of the machining direction on the machining result for remelting workpieces without precoating with linearly polarized and p-polarized laser radiation as a function of the angle of incidence ⁇ .
  • the output power of the laser was 4 kW and the feed speed v was 200 mm / min; the workpiece was machined in a horizontal position.
  • the lower curve shows the remelted area as a function of the angle of incidence for remelting during slow processing (see FIG. 1 right * e arrangement), while the upper curve represents the same for the piercing machining according to the invention.
  • For the measuring points at 70 °, cross sections of the remelted surface are shown for both cases. At an angle of incidence of 70 °, the remelted volume can be increased by more than 40% with a piercing machining direction rather than a sluggish one.
  • the optimal angle of incidence or parallel portion of the E-vector of the polarized laser radiation for a specific precoating need not be identical to the angle of incidence or the E-vector for a maximum absorption rate . Rather, the proportion of the reflected radiation that hits the precoating after the piercing is also important here (cf. FIG. 3).

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Laser Beam Processing (AREA)

Abstract

Description d'un procédé de refusion de surfaces de pièces par rayonnement laser, notamment de surfaces préalablement revêtues. L'invention se caractérise en ce que le traitement s'effectue avec un rayon laser qui agit dans le sens de traitement sur les surfaces des pièces, avec un angle d'incidence différent de zéro de manière que le processus de refusion s'opère par traitement par piqûres. Le rayonnement laser est avantageusement polarisé linéairement (p-polarisé) et le degré d'absorption est réglé par la sélection d'un angle d'incidence approprié, conformément aux courbes de réflexion de Fresnel.
PCT/DE1993/000328 1992-04-10 1993-04-09 Procede de refusion de surfaces de pieces par rayonnement laser WO1993021360A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DEP4212035.7 1992-04-10
DE19924212035 DE4212035C2 (de) 1992-04-10 1992-04-10 Verfahren zum Umschmelzen von Oberflächen von Werkstücken mit Laserstrahlung

Publications (1)

Publication Number Publication Date
WO1993021360A1 true WO1993021360A1 (fr) 1993-10-28

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Application Number Title Priority Date Filing Date
PCT/DE1993/000328 WO1993021360A1 (fr) 1992-04-10 1993-04-09 Procede de refusion de surfaces de pieces par rayonnement laser

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DE (1) DE4212035C2 (fr)
WO (1) WO1993021360A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998015672A1 (fr) * 1995-10-05 1998-04-16 Blz Bayerisches Laserzentrum Gemeinnützige Forsch Ungsgesellschaft Mbh Procede et dispositif de fabrication d'un outil de coupe
WO2002072916A1 (fr) * 2001-02-21 2002-09-19 Fortum Oyj Procede de revetement de cuivre ou d'alliage de cuivre
AT411654B (de) * 2001-06-25 2004-04-26 Boehler Ybbstal Band Gmbh & Co Verfahren zur herstellung eines zerspanungswerkzeuges
CN103103520A (zh) * 2013-01-14 2013-05-15 温州大学 一种核电阀门阀杆表面激光复合强化的工艺

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114952009B (zh) * 2022-04-18 2024-02-02 哈尔滨工大焊接科技有限公司 一种真空激光重熔表面改性方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1988008353A1 (fr) * 1987-04-25 1988-11-03 Fraunhofer-Gesellschaft Zur Förderung Der Angewand Dispositif et procede d'assemblage par rayonnement laser
WO1989010434A1 (fr) * 1988-04-23 1989-11-02 Glyco-Metall-Werke Daelen & Loos Gmbh Materiau ou piece stratifie avec une couche fonctionnelle, notamment une couche de glissement, appliquee sur une couche de support et ayant la structure d'une dispersion solide mais fusible
DD281141A5 (de) * 1987-10-14 1990-08-01 Fz Des Werkzeugmaschinenbaues Karl-Marx-Stadt,Dd Verfahren zur laserbearbeitung von vorzugsweise hochreflektierenden werkstuecken

Family Cites Families (5)

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Publication number Priority date Publication date Assignee Title
DE3126953C2 (de) * 1981-07-08 1983-07-21 Arnold, Peter, Dr., 8000 München Verfahren zur thermischen Behandlung der Oberfläche von Werkstücken mittels eines linear polarisierten Laserstrahls
IT1179063B (it) * 1984-08-20 1987-09-16 Fiat Auto Spa Apparecchiatura per effettuare trattamenti su pezzi metallici mediante laser di potenza
JPS6237350A (ja) * 1985-08-12 1987-02-18 Toshiba Corp 表面熱処理装置
JP2603873B2 (ja) * 1989-01-09 1997-04-23 三菱電機株式会社 レ−ザ加工機及びレ−ザ加工方法
DE4018355A1 (de) * 1990-06-08 1992-01-09 Fraunhofer Ges Forschung Verfahren zur oberflaechenbehandlung von werkstuecken mit laserstrahlung

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1988008353A1 (fr) * 1987-04-25 1988-11-03 Fraunhofer-Gesellschaft Zur Förderung Der Angewand Dispositif et procede d'assemblage par rayonnement laser
DD281141A5 (de) * 1987-10-14 1990-08-01 Fz Des Werkzeugmaschinenbaues Karl-Marx-Stadt,Dd Verfahren zur laserbearbeitung von vorzugsweise hochreflektierenden werkstuecken
WO1989010434A1 (fr) * 1988-04-23 1989-11-02 Glyco-Metall-Werke Daelen & Loos Gmbh Materiau ou piece stratifie avec une couche fonctionnelle, notamment une couche de glissement, appliquee sur une couche de support et ayant la structure d'une dispersion solide mais fusible

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998015672A1 (fr) * 1995-10-05 1998-04-16 Blz Bayerisches Laserzentrum Gemeinnützige Forsch Ungsgesellschaft Mbh Procede et dispositif de fabrication d'un outil de coupe
US6316065B1 (en) 1995-10-05 2001-11-13 Ble Bayerisches Laserzentrum Gemeinnutzige Forschungsgesellschaft Mbh Process and device for manufacturing a cutting tool
WO2002072916A1 (fr) * 2001-02-21 2002-09-19 Fortum Oyj Procede de revetement de cuivre ou d'alliage de cuivre
AT411654B (de) * 2001-06-25 2004-04-26 Boehler Ybbstal Band Gmbh & Co Verfahren zur herstellung eines zerspanungswerkzeuges
CN103103520A (zh) * 2013-01-14 2013-05-15 温州大学 一种核电阀门阀杆表面激光复合强化的工艺

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Publication number Publication date
DE4212035C2 (de) 1996-08-14
DE4212035A1 (de) 1993-10-14

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